Thanks for all the suggestions! I wrote him this morning and told him if he wants superior cancellation go with the Bose QC25's (wired so he won't have any issues with using Bluetooth on a flight). But if he wants to sacrifice some NC and get better SQ, then let me know and I'll dig a little deeper.

Budget isn't too big a deal. His exact words were "I'll pay up to $500 if it can scratch my back too."

In that price range you can get the Shure SE535-LTD In-Ears (they red ones).

They have superb noise-isolation, are easy to stow away in a jacket and don't need any charging or batteries. Easy choice in my book, they will blow any headphone in that price range clear out of the water.